This invention relates to tubing and methods of making tubing for conveying liquids. More specifically, embodiments of the present invention are directed to narrow internal diameter tubing. Embodiments of the present invention have particular utility for use in chromatographic equipment which use tubing to convey fluids under precise flow regimes.
It is difficult to make very small narrow internal diameter tubing, with an internal diameter in the region of about 0.002-0.005 inches (0.0508-0.127 mm).
Many known types of narrow tubing exhibit a poor internal finish, which can lead to wide internal diameter fluctuations, a lack of internal diameter/external diameter concentricity and possibly flow obstructions. These problems are due to the rigours of the manufacturing process using multiple drawings. Multiple drawings are required to make tubes of such small internal diameter. The resulting tubing is undesirable to use because it results in a reduced efficiency of the chromatographic equipment.
It is preferable that the tubing is robust in use. It is preferable that the tubing can bend without becoming kinked.
It is preferable to have tubing with a better internal finish, that is sufficiently robust.